I need update iPhone 6 version to ios12.5.6

"I need update iPhone 6 version to ios12.5.6"

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Updating an iPhone 6 to iOS12.5.6:

Update Using a Computer:

Have a Computer Handy? If so, try using a computer to update. Go here: Update your iPhone Using a Computer - User Tip. If any updates are availabe, they will install, sure enough.

Just follow the steps in this Apple article, either wirelessly or through a computer:

Update your iPhone or iPad - Apple Support

You can’t update to 12.5.6, but you can update to 12.5.7.